Expansion of laser-generated plumes near the plasma ignition threshold

Abstract

24) Niwa, 0.; Morita, M.; Tabei, N. J. Nectroanal. Chem. InterfacialNectrochem. 1989, 267, 291-297. (25) Abramowitz, M., Stegun. I. A., Eds.; Handbook of Mathematical Functions; Dover Publications: New York, 1970; pp 589-598. 126) Baur. J.; Wiahtman. R. M. J. Nectroanal. Chem. Interfacial Nectro-(30) Wipf, D. 0.; Wightman, R. M. Anal. Chem. 1988, 60, 2460-2464. (31) Cammarata, V.; Talham, D. R.; Crooks, R. M.; Wrighton, M. S. J.Expansion of laser-produced plumes on a solid-vacuum interface during and after the laser shot was Investigated theoretically, Incorporating several new features Into our previous one-component one-dimensional hydrodynamic model. Time development of density, velocity, temperature, and pressure proflles was calculated at laser Irradiances below and above the plasma lgnltlon threshold. The estlmated velocity of ions released from the plume was close to the measured values. The fast spreading of the blow-off material under the laser vaporization regime and the long lifetime of the relatively compact plasma core above the ignition threshold were predicted in agreement with experimental observatlons. Calculated surface recession due to evaporation provided a lower bound to the measured crater depth, whereas the calculated melt depth proved to be a realistic upper limit.

Pulsed laser ablation and deposition of thin films

“…17 DLC films, which are hard and smooth, generally inert, exhibit low friction and adhere well to many substrates, find widespread use as wear resistant coatings. Target weight loss measurements show that, under our typical operating conditions (incident fluence ~20 J cm 22 , ~20 ns pulse duration), ~10 15 C atoms (or their mass equivalent) are removed per pulse. It is worth pausing for a moment to consider the consequences of this number.…”

“…14 Also shown in Figs. 3(e) and 3(f) are the results of model calculations employing a 1-D second-order heat conduction model (defined in ref. 15) illustrating the time dependence of the surface temperature (T S ), and the temperature at a number of different penetration depths, D, within the localised laser interaction zone. The incident laser pulse used in these calculations is assumed to have a Gaussian temporal profile of 30 ns full width half maximum (FWHM) and to peak 60 ns after the start of the simulation.…”

An all-optical ion-loading technique for scalable microtrap architectures

“…Here we are principally concerned with the low fluence regime, in which thermal processes are dominant. If the laser pulse duration is much shorter than the timescale for thermal conduction processes then the region of the target that is irradiated by the laser may be locally heated to high temperatures [14]. This can result in melting, sublimation or desorption of material in the affected region.…”

A study of fast and metastable dissociations of adenine-thymine binary-base oligonucleotides by using positive-ion MALDI-TOF mass spectrometry

“…It is generally believed that the matrix molecules play a critical role in absorbing the laser photons and distributing the energy in such a way that the embedded analyte molecules would be desorbed and ionized with minimum internal energy. Different models have been proposed [33][34][35][36] to explain the desorption and ionization phenomena under UV-MALDI conditions. In general, it is believed that some sorts of bottleneck [37] exist in the transfer of internal energy from the highly excited matrix moieties to the analyte ions.…”